Toothbrush and method for manufacturing toothbrush

ABSTRACT

Provided are a toothbrush in which a tapered surface is formed on a tip part of synthetic resin fibers forming a brush and a fiber surface including the fiber tip part is coated with minerals and the toothbrush is provided with a bristle tip (fiber) having appropriate bending strength, and a manufacturing method of the toothbrush. The toothbrush  1  includes a brush in which a mineral component layer is formed on a surface of a synthetic resin fiber  4.  The synthetic resin fiber  4   a  having a tapered surface  4   a   1  which is formed in a range of 1 mm to 8 mm from a tip occupies 90% or more of the synthetic resin fibers  4  ( 4   a,    4   b ), and bending strength of the brush at a position of 1 mm from a leading edge of the brush  3  (the synthetic resin fibers  4  ( 4   a,    4   b )) is 0.60 N/cm 2  to 2.00 N/cm 2 .

TECHNICAL FIELD

The present invention relates to a toothbrush and a manufacturing method of the toothbrush, and particularly, to a toothbrush in which a surface of synthetic resin fibers forming a brush is coated with minerals and a manufacturing method of the toothbrush.

BACKGROUND ART

There are conventionally sold toothbrushes in which a surface of synthetic resin fibers forming a brush is coated with mineral components. The mineral components with which the surface of the fibers forming the brush is coated are as described, for example, in PTL 1 to have various effects such as water repellency and prevention of attachment or reproduction of bacteria, and the toothbrush coated with the mineral components has an advantage that toothpaste is not necessary and cleaning in the mouth is made to be possible.

Incidentally the synthetic resin fibers coated with the mineral components generally adopt nylon fibers each of which is formed in a so-called columnar shape. Accordingly, a relatively flat and wide parts of tooth such as a tooth face or gum is easy to be brushed, but there is a problem in that when the face is brushed excessively, the gum is damaged by an edge portion between an end face (upper face) and a side face of the columnar fiber. In addition, the tip part of the columnar fiber is difficult to enter in a narrow location such as the tooth face or periodontal pocket, creating a problem of leaving such portions unbrushed.

As a method for solving the foregoing problems, for example, as shown in PTL 2, a tapered processing is disclosed in which a tapered surface is formed on the tip part of the synthetic resin fiber by chemical treatment to narrow the tip part of the columnar fiber. The tapered processing can be also applied to the toothbrush in which the surface of the synthetic resin fibers forming the brush is coated with mineral components.

The toothbrush that is subjected to the tapered processing and is coated with the mineral components enables the tip part of the fiber to enter the narrow location such as the tooth face or periodontal pocket, and can brush the tooth face, the gum, and portions between teeth without unbrushed portion being left.

CITATION LIST Patent Literature

-   PTL 1: Unexamined Patent Application Publication No. 2004-237248 -   PTL 2: Unexamined Patent Application Publication No. 2010-233781

SUMMARY OF INVENTION Technical Problem

Incidentally, in the toothbrush in which the surface of the synthetic resin fibers forming the brush is coated with the mineral components, the surface of the nylon fiber is made smooth by the chemical treatment and the coated mineral component is easy to drop out, therefore arises a technical problem in that it is impossible to obtain the function of the water repellency or prevention of attachment or reproduction of bacteria for a long period of time.

The tapered surface formed on the tip part of the synthetic resin fiber is formed to the extent of 2 mm to 5 mm in view of a size of the periodontal pocket or the like.

In a case of forming the tapered surface by the chemical treatment, the tapered surface becomes longer by a capillary force than an expected tapered surface length and also the fiber tip becomes narrow, and this leads to the weakening of bending strength of the bristle tip (tip part of the fiber). Therefore, arises a technical problem in that the bristle tip (tip part of the fiber) gets bent against the wide and nearly flat sections such as the gum portion or the tooth face and the cleaning capability is insufficient.

To solve the technical problems, the inventors have eagerly studied toothbrushes in which the surface of the synthetic resin fibers forming the brush is coated with the minerals, and manufacturing methods for the toothbrushes. The inventors have studied toothbrushes in which a tapered surface having a predetermined length can be obtained on the premise that the tapered processing of the tip part of the fiber is carried out with mechanical polishing, the surface of the fiber becomes rough, fixation of mineral components improves, and it is possible to obtain the function of the water repellency or prevention of attachment or reproduction of bacteria for a long period of time.

Incidentally the inventors have had the following findings. In a case where the tapered surface is mechanically formed on the tip part of the fiber made of the synthetic resin using polishing processing only, the tip part of the fiber cannot enter the narrow location such as the tooth face or the periodontal pocket when the length of the tapered surface is 1 mm or shorter. In that case, the bending strength of the bristle tip (tip part of the fiber) is strong, the flexibility is not obtained and feeling of use is not good. On the other hand, the inventors have had the following findings. As the length of the tapered surface is longer than 1 mm, the tip part of the synthetic resin fiber is more excessively polished, the fiber (bristle tip) is bent more than the tooth brush subjected to tapered processing by the chemical treatment, whereby the cleaning capability becomes insufficient and durability in use degrades.

The inventors have discovered a manufacturing method of the toothbrush based upon the above findings as described hereinafter. At least the tapered processing of the fiber tip part is performed with the mechanical polishing in a state where the synthetic resin fiber is dissolved and swelled before the process of coating the synthetic resin fiber with the mineral component; as a result, the tapered surface having a predetermined length can be obtained. In addition, fixation of the coated mineral component can be improved, the bristle tip (tip part of the fiber) having the appropriate bending strength is provided, and it is possible to allow the bristle tip (tip part of the fiber) to enter the narrow location such as the tooth face or periodontal pocket to brush the tooth face, and the gum and the interdentium.

The present invention has an object of providing a toothbrush in which a tapered surface is formed on each tip part of synthetic resin fibers forming a brush and a mineral component layer is formed on a fiber surface including the fiber tip part, the toothbrush being provided with a bristle tip (fiber) having appropriate bending strength, and a manufacturing method of the toothbrush.

Solution to Problem

In order to achieve the above object, the present invention provides a toothbrush including: a brush in which a mineral component layer is formed on a surface of a synthetic resin fiber, wherein the synthetic resin fiber having a tapered surface occupies 90% or more of the synthetic resin fibers forming the brush and the tapered surface is formed in a range of 1 mm to 8 mm from a tip, and bending strength of the brush in a position of 1 mm from a brush leading edge is 0.60 N/cm² to 2.00 N/cm².

Since the synthetic resin fibers having the tapered surface occupies 90% or more of the synthetic resin fibers forming the brush and the tapered surface is formed in a range of 1 mm to 8 mm from the tip, it is possible to allow the tip part of the fiber to enter the narrow location such as the tooth face or periodontal pocket to obtain a sufficient cleaning capability.

In addition, since the bending strength of the brush in a position of 1 mm from the brush leading edge is in a range of 0.60 N/cm² to 2.00 N/cm², the appropriate bending strength of the bristle tip (tip part of the fiber) can be obtained and a good feeling of use with the soft feeling (flexibility) can be obtained.

Furthermore, it is possible to improve a removal effect of dirt such as dental plaque accumulated in narrow locations such as interdentium or periodontal pockets in between teeth and gums, in wide locations such as tooth faces or the like, and a soft brush touch on sensory sensitive locations such as the periodontal pocket or the gum can be obtained, thus making it possible to obtain a toothbrush of good feeling of use.

Here, irregularities are preferably formed on the tapered surface. In this way, in a case where irregularities are formed on the tapered surface, the fixation of the mineral component layer is improved, it is possible to obtain the effect of the mineral component for a long period of time.

In order to achieve the above object, the present invention provides a manufacturing method of the toothbrush, including the steps of: bundling the synthetic resin fibers to produce a synthetic resin fiber assembly; immersing the synthetic resin fiber assembly in a solution bath in which a soluble liquid is accommodated; moving the synthetic resin fiber assembly up and down from an upper side of a polishing/rubbing body; causing the synthetic resin fiber assembly to come into contact with a polishing/rubbing blade for a predetermined time; dissolving and swelling a surface of the synthetic resin fiber; and scrubbing off the surface of the synthetic resin fiber by the polishing/rubbing blade, to form the tapered surface.

In this way, the tapered surface is formed by dissolving and swelling the surface of the synthetic resin fiber, and scrubbing off the surface of the synthetic resin fiber by the polishing/rubbing blade. Therefore even if the tapered surface having a length of 1 mm or longer is formed, the brush having an appropriate bending strength can be obtained without excessive polishing to the tip part of the synthetic resin fiber. That is, it is possible to easily manufacture the toothbrush in which the tapered surface is formed in a range of 1 mm to 8 mm from the tip and the bending strength of the brush in a position of 1 mm from the brush leading edge is in a range of 0.60 N/cm² to 2.00 N/cm².

Here, after the step of forming the tapered surface, the synthetic resin fiber assembly is preferably immersed in mineral water to form a mineral component layer. That is, the tapered surface is formed by dissolving and swelling the surface of the synthetic resin fiber, and scrubbing off the surface of the synthetic resin fiber by the polishing/rubbing blade. Therefore the surface roughness of the tapered surface becomes large, the fixation of the mineral component layer thereon is improved and the durability thereof improves.

Advantageous Effects of Invention

According to the present invention, the present invention can provide the toothbrush in which the tapered surface is formed on the tip part of the synthetic resin fibers forming the brush and the mineral component layer is formed on the fiber surface including the fiber tip part, the toothbrush being provided with the bristle tip (fiber) having the appropriate bending strength, and the manufacturing method of the toothbrush.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side view illustrating a toothbrush according to an embodiment of the present invention.

FIG. 2 is a side view illustrating synthetic resin fibers forming the brush illustrated in FIG. 1.

FIG. 3 is a schematic configuration diagram illustrating a manufacturing apparatus used in a manufacturing method for the toothbrush according to the present invention.

FIG. 4 is an enlarged view illustrating an essential part of the manufacturing apparatus illustrated in FIG. 3.

FIG. 5 is a schematic diagram illustrating a polishing/rubbing body used in the manufacturing apparatus illustrated in FIG. 3.

FIG. 6 is a perspective view illustrating an example of a synthetic resin fiber processed by the manufacturing apparatus illustrated in FIG. 3.

FIG. 7 is a perspective view illustrating another example of a synthetic resin fiber processed by the manufacturing apparatus illustrated in FIG. 3.

FIG. 8 is a schematic diagram illustrating a manufacturing process of a toothbrush.

FIG. 9 is a side view schematically illustrating a measurement apparatus for measuring bending strength of a brush.

FIG. 10 is a side view explaining a measurement method by the measurement apparatus in FIG. 9.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an explanation will be made of an embodiment of the present invention with reference to the drawings. FIG. 1 is a side view illustrating a toothbrush according to an embodiment of the present invention. In the figure, a toothbrush is denoted by reference sign 1, a handle of the toothbrush 1 is denoted by reference sign 2 and a brush provided at the tip part of the handle of the tooth brush 1 is denoted by reference sign 3. The brush 3 is formed by implanting fiber bundles 3A formed of a plurality of synthetic resin fibers 4 at plural locations of the tip part of the handle 2 of the toothbrush 1.

An example of a material of the synthetic resin fibers 4 forming the brush 3 may include a polyester resin such as polybutylene terephthalate, polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate or polybutylene naphthalate, a polyolefin resin such as polyethylene or polypropylene, a polyamide resin such as nylon 6, nylon 610 or nylon 612, an acrylate resin, a polyurethane resin, a polyacethale resin, a polycarbonate resin, a polyether resin, a polyphenylene resin or a polyvinyl resin.

The synthetic resin fiber having approximately 0.10 mm to 0.25 mm in diameter can have appropriate flexibility and a suppression effect of bending or broken, and therefore can be used suitably as a brush of a toothbrush. The above diameter is a diameter of a columnar part (part where a tapered surface 4 a 1 is not formed).

The number of the fibers in one bundle formed by assembling the synthetic resin fibers 4 can be set as needed, but 40 to 70 fibers can be typically used as the number of fibers protruding out of one implant hole 2 a (refer to FIG. 8(c)). The number of the fiber bundles 3A implanted in the tip part of the handle 2 in the tooth brush 1 can be set as needed, but typically 10 to 25 implant locations can be preferably adopted as the number of the fiber bundles 3A.

The synthetic resin fibers 4 forming the brush 3 include tapered fibers 4 a each having diameter formed to be gradually smaller toward the tip and a tip part on which a taper, tapered surface 4 a 1 is formed, and columnar non-tapered fibers 4 b each having a tip part on which a taper, tapered surface is not formed and an end face 4 b 1.

Moreover, 90% or more in number of the entire synthetic resin fibers is composed of the tapered fibers 4 a on each of which the tapered surface is formed. Furthermore, the brush 3 may be formed by the tapered fibers 4 a only.

A length X of the tapered surface 4 a 1 formed on the tapered fiber 4 a is formed in a range of 1 mm to 8 mm. This is set in a range of 1 mm to 8 mm in consideration of a size of a periodontal pocket or the like (responding to a periodontal pocket having a periodontal disease).

Since the brush 3 thus configured includes a great number of the tapered fibers 4 a, the bending strength can increase toward the rear side from a tip part 3 a through a tapered part 3 b and to a straight body part 3 c, which can improve feelings of use.

That is, the tip part of the tapered fiber 4 a can be allowed to enter the narrow locations such as the interdentium, and the periodontal pocket in between the tooth and the gum. Since the bending strength can increase toward the rear side through the tapered part 3 b to the straight body part 3 c, it is possible to achieve easy removal of dirt such as dental plaque accumulated in the wide location such as the tooth face, and further, a soft brush touch on sensory sensitive location such as the periodontal pocket or the gum, and good feelings of use.

For this purpose, the tapered fibers 4 a preferably occupy at least 90% or more of the brush 3 as a whole.

In addition, it is preferable that in the brush 3, as illustrated in FIG. 1, the bending strength in a position of 1 mm from the tip part 3 a of the brush 3 toward a direction of the handle is in a range of 0.60 to 2.00 N/cm².

Here, the reason why the bending strength in the position of 1 mm from the tip part 3 a of the brush 3 toward the direction of the handle is set as a reference is that a clearance between the tooth and the gum corresponding to the periodontal pocket is 1 mm to 2 mm for healthy persons, and the bending strength at the time when the tip of the brush 3 (synthetic resin fiber) enters the clearance has an influence on an entering extent of the synthetic resin fiber into the clearance and the feelings of use of the tooth brush.

In a case where the bending strength is in a range of 0.60 to 2.00 N/cm², it is possible to achieve easy removal of dirt such as dental plaque accumulated in the wide location such as the tooth face, and furthermore, a soft brush touch on sensory sensitive location such as the periodontal pocket or the gum, and the good feelings of use.

Here, the bending strength is a magnitude in strength to be measured by a measurement method as described hereinafter.

Setting the bending strength of the toothbrush 3 to have a range of 0.60 to 2.00 N/cm² at the position of 1 mm from the tip part 3 a of the toothbrush 3 toward the direction of the handle is achieved by suitably defining quality of material of the synthetic resin fiber 4, a diameter of the fiber 4, a mixing ratio of the tapered fibers 4 a and the non-tapered fibers 4 b, a length of the tapered surface 4 a 1 of the tapered fiber 4 a (refer to a reference sign X in FIG. 2), the number of the fibers 4 forming one fiber bundle 3A, the number of the fiber bundles 3A forming the brush 3, a shape of the brush 3 and a shape (a diameter and length) of an entire brush.

Each surface of the synthetic resin fibers 4 forming the brush 3 is subjected to coating processing with mineral components, and a mineral component layer is formed on the surface (not shown).

The component of the mineral component layer can be set as needed; the mineral component having, for example, calcium 15 to 20 (mg/L), magnesium 2.5 to 3.0 (mg/L), strontium 0.04 to 0.05 (mg/L), potassium 2.9 to 4.6 (mg/L), iron<0.1 (mg/L), sodium 14 to 21 (mg/L), silicon 2.3 to 6.7 (mg/L), aluminum<2.5 (mg/L), copper<0.02 (mg/L) or zinc<0.01 (mg/L), which are described in PTL 1, can be used as a primary component.

For forming the mineral component layer, after the synthetic resin fiber 4 is immersed in mineral water containing the above mineral components, the synthetic resin fiber 4 is applied with a cloth or a brush, or heated to a temperature of 50° C. or higher, or placed under a pressure environment of 0.15 MPa or more or the like. Thereby the mineral component layer can be formed on the surface of the synthetic resin fiber 4.

Next, an explanation will be made of a manufacturing method of the toothbrush according to the present invention with reference to FIG. 3 to FIG. 8.

First, as illustrated in FIG. 3, a fiber assembly 5 is produced by bundling the synthetic resin fibers 4 having a predetermined length by a predetermined number. Next, the produced fiber assembly 5 is attached on a holder 11, and the synthetic resin fibers 4 of the fiber assembly 5 are subjected to tapered processing.

The tapered processing uses a soluble or swelling treatment liquid to the synthetic resin fiber 4, and is performed while swelling and polishing/rubbing the synthetic resin fiber 4. The treatment liquid in use differs in each kind of the synthetic resin fiber; for example, in a case of a polyester resin fiber, a sodium hydroxide solution is generally used, and in a case of a polyamide fiber, a mixed liquid of meta-cresol and a calcium chlorite and methanol solution is used.

The tapered processing of the synthetic resin fibers using this treatment liquid will be explained with reference to FIG. 3 to FIG. 5 by taking a case of using nylon fibers as an example.

In this processing method, as denoted by reference signs 10A, 10B, and 10C, a work processing apparatus in which a plurality of solution baths are serially arrayed is used. In a case of this processing method, as each treatment liquid used for polishing/rubbing and cleaning of nylon fibers, a saturated calcium chloride and methanol solution is used as a soluble liquid of the first solution bath 10A, a mixing liquid of calcium chloride 15% (by weight) and methanol 85% (by weight) is used as a soluble liquid of the second solution bath 10B, and methanol (100%) is used as a cleaning liquid in the cleaning liquid bath 10C.

A polishing/rubbing body 12 for polishing and rubbing the nylon fibers of the nylon fiber assembly 5 is provided in each of the first solution bath 10A and the second solution bath 10B. The polishing/rubbing body 12 includes polishing/rubbing blades 13 in a thin plate-shaped disk type, a rotational shaft 14 on which a plurality of the polishing/rubbing blades 13 are arrayed in parallel by predetermined intervals, and a spacer 15 arranged in every interval of the polishing/rubbing blades 13.

At least a part of the polishing/rubbing body 12 (the polishing/rubbing blades 13) is arranged to be submerged in the soluble liquid bath. The polishing/rubbing body 12 is arranged also in the cleaning bath 10C, but since the cleaning liquid has a non-swelling property to nylon fibers, the polishing/rubbing are hardly performed in this section.

In a case of processing the nylon fiber assembly 5 attached on the tip of the holder 11 with this apparatus, while the holder 11 on which the nylon fiber assembly 5 is attached is being moved up and down from an upper side of the polishing/rubbing body 12, and being moved from the paper deep side to the paper near side FIG. 3 (left-right direction in FIG. 5), the nylon fiber assembly 5 is made come into contact with the polishing/rubbing blade 13 for a predetermined time.

When the soluble liquid in the first solution bath 10A adheres to the nylon fiber assembly 5, the surface of the nylon fiber is dissolved and swelled, and is scrubbed off by the polishing/rubbing blade 13.

That is, as illustrated in FIG. 5, since a combing blade 13 a in a saw tooth shape is formed on the polishing/rubbing blade 13, the polishing/rubbing blade 13 comes into contact with the fibers of the nylon fiber assembly 5 to comb the fibers to repeat the dissolution and rubbing. At this time, by controlling a velocity of the up and down movement of the nylon fiber assembly 5 and the moving velocity thereof from the paper deep side to the paper near side in FIG. 3 (in the left-right direction in FIG. 5), the nylon fibers forming the nylon fiber assembly 5 are processed in a tapered shape. An entire shape of the nylon fiber assembly 5 is formed in a tapered shape to become thinner toward the tip part.

The polishing/rubbing blade 13 may be fixed, but the polishing/rubbing blade 13 may be formed to rotate by the up and down movement of the nylon fiber assembly 5 and the movement of the nylon fiber assembly 5 from the paper deep side to the paper near side in FIG. 3 (in the left-right direction in FIG. 5). In addition, by the up and down movement of the nylon fiber assembly 5 and the lateral movement of the nylon fiber assembly 5 from the paper deep side to the paper near side in FIG. 3 (in the left-right direction in FIG. 5), the nylon fiber is processed in the tapered shape, but the nylon fiber may be processed in the tapered shape by moving the nylon fiber assembly 5 up and down without the above lateral movement of the nylon fiber assembly 5.

Next, the nylon fiber assembly 5 is moved to the second solution bath 10B to move up and down and again come into contact with the polishing/rubbing body 12 for a predetermined time. The polishing/rubbing in the second solution bath 10B produces a polishing and rubbing amount in addition to the polishing and rubbing amount of the first solution bath 10A, and a basic function is the same as that of the first solution bath 10A.

That is, when the velocity of the up and down movement of the nylon fiber assembly 5 is controlled, the nylon fibers forming the fiber assembly 5 each are formed as the fiber 4 a having the tapered surface 4 a 1 as illustrated in FIG. 6.

Finally the nylon fiber assembly 5 moves to the cleaning bath 10C and comes into contact with the polishing/rubbing body 12 for a predetermined time to clean the fibers 4 a, thus completing the processing of one end of the nylon fiber assembly 5.

In the method as already described, by controlling the movement (movement distance) of the synthetic resin fiber assembly 5 in the upper-lower direction and the movement of the synthetic resin fiber assembly 5 from the paper deep side to the paper near side in FIG. 3 (in the left-right direction in FIG. 5), a plurality of beaded projecting portions 4 a 2 are formed on a surface part of the tapered surface 4 a 1 in an axial direction of the fiber. At this time, a recessed portion 4 a 3 is formed between the adjacent projecting portions 4 a 2. That is, the projecting portion and recessed portion alternately and sequentially appear in the axial direction of the fiber by the beaded projecting portions 4 a 2 and recessed portions 4 a 3.

In the method as already described, by rotating the polishing/rubbing body 12, further moving the synthetic resin fiber assembly 5 up and down while rotating it, and controlling rotational velocities of the polishing/rubbing body 12 and the synthetic resin fiber assembly 5 as well, a shape of the tapered surface may be further controlled (refer to virtual line arrows in FIG. 3 and FIG. 5). On this occasion, since the polishing/rubbing body 12 itself rotates, it is unnecessary to move the synthetic resin fiber assembly 5 (holder 11) from the paper deep side to the paper near side in FIG. 3 (in the left-right direction in FIG. 5) as described before, and the synthetic resin fiber assembly 5 may be moved up and down while rotating.

Further in the same way, the other end of the synthetic resin fiber assembly 5 is also subjected to the processing of forming the tapered surface 4 a 1.

In addition, after the synthetic resin fiber 5 is immersed in mineral water containing the above mineral components, the synthetic resin fiber 5 is applied with a cloth or a brush, or heated to a temperature of 50° C. or higher, or placed under a pressure environment of 0.15 MPa or more or the like. Thereby the mineral component layer can be formed on the surface of the synthetic resin fiber 5.

After performing the above processes, the synthetic resin fiber assembly 5 is dried, thereby forming the mineral component layer on the surface of the synthetic resin fiber assembly 5.

As described above, since the tapered surface 4 a 1 is formed by the rubbing of the saw-tooth shaped combing blade 13 a, the surface roughness becomes greater than before the processing. Therefore it is easier to form the mineral component layer and the mineral component layer is formed to be hard to drop off (good in fixation).

Particularly in the synthetic resin fiber 4 in which the recessed portion and projecting portion are alternately arranged by the beaded projecting portion 4 a 2 and recessed portion 4 a 3, the mineral components can be more firmly attached thereon.

Subsequently as illustrated in FIG. 8(a), there is prepared a fiber bundle in which the number of the tapered fibers 4 a occupies at least 90% or more of the entire fibers, as illustrated in FIG. 8(b), a central part of the fiber bundle is bent to form a U-letter shape, and the central part is inserted/fixed in the implant hole 2 a formed in the handle 2 together with an engagement element 2 b such as a wire, thus completing the toothbrush 1 (refer to FIG. 8(c)).

Next, an explanation will be made of the measurement method of the bending strength of a brush.

A measurement apparatus schematically illustrated in FIG. 9 is used for the measurement. The measurement apparatus is provided with a stand portion 21 erected on a base platform 20 as an elevating mechanism. A groove portion 21 a linearly extending up and down is formed in the stand portion 21, and a slider 22 is provided, capable of going up and down along the groove portion 21 a by a screw mechanism or the like. MX-500N made by IMADA CO., LTD can be used as the elevating mechanism.

The slider 22 is provided with a load meter 26 for measuring loads applied on a gauge head 25. MODLDS2-2N made by IMADA CO., LTD can be used as the load meter 26.

As illustrated in the figure, the gauge head 25 of the load meter 26 is arranged for the tip to project laterally (horizontal direction), and before measuring the load, as illustrated in FIG. 10(a), the brush 3 is arranged such that the brush 3 of the toothbrush 1 as a measured body is positioned downward of a tip surface 25 a of the gauge head 25. The tooth brush 1 is configured to be horizontally movable by a fixing tool (not shown) and capable of changing an initial position of the brush 3. A vertical direction of the fixing tool is configured to be fixed and not to move.

On the other hand, the gauge head 25 of the load meter 26 is configured to be movable in a vertical direction and not to move in a horizontal direction. The fixing tool is moved in the horizontal direction to position the tip surface 25 a of the gauge head 25 right above a position at a predetermined distance d (1 mm) in a vertical direction to the handle from the tip part 3 a of the brush 3, and the arrangement is defined as an initial position.

The reason why the predetermined distance d is set to 1 mm is to consider that a clearance between a tooth and a gum of a healthy person is generally in a range of 1 mm to 2 mm as described before.

In the measurement apparatus of this construction, in a case of measuring the bending strength of the brush 3, the load meter 26 goes down together with the slider 22 from a state of the initial position illustrated in FIG. 10(a).

As a result, the gauge head 25 of the load meter 26 goes down, and, as illustrated in FIG. 10(b), the gauge head 25 comes into contact with the tip side of the brush 3 from above, bringing in a state where the tip side of the brush 3 is pressed and bent. The tip side of the brush 3 is pressed against the tip surface 25 a of the gauge head 25.

In this state, a horizontal predetermined load F acts on the gauge head 25; a load measurement value is displayed on a display window 26 a of the load meter 26. The maximum value of this measurement value is defined as a value of the bending strength. When the load meter 26 further goes down, as illustrated in FIG. 10(c), the brush 3 becomes in a state of being separated from the gauge head 25. In the toothbrush 3 according to the present invention, the maximum value (value of the bending strength) of the load measurement value displayed on the display window 26 a of the load meter 26 is in a range of 0.60 to 2.00 N/cm².

EXAMPLES

(Experiment 1)

Nylon fiber was used as a material of synthetic resin fiber in a brush, and a length of the fiber was set to 7 mm, 10 mm and 12 mm, and the fibers having a diameter of 0.10 mm, 0.18 mm and 0.25 mm were used. A length of the tapered fiber from the tip part of the tapered surface was set to 1.0 mm, 5.0 mm and 8.0 mm, and a mixing ratio of the tapered fiber was set to 80%, 85%, 90% and 100% of the entirety. The number of the fibers forming one bundle of the fibers was set to 40 to 70, and the bundle number forming the brush was set to 10 to 25. A planar shape of the brush was set to a rectangular shape; a length of the brush in a longitudinal direction of a handle was set to 10 mm to 25 mm, and a length of the brush in a lateral direction of the handle was set to 7 mm to 13 mm.

In regard to the brush in which the length of the fiber was set to 7 mm to 12 mm; the diameter thereof was set to 0.10 mm to 0.25 mm; the length of the tapered fiber from the tip part of the tapered surface was set to 1 mm to 8 mm, and the mixing ratio of the tapered fiber was set to 90% or more of the entirety. It was confirmed that the brush allows the bristle tip (tip part of the fiber) to enter the narrow location such as the tooth face or periodontal pocket and to brush the tooth face, the gum, and the interdentium without leaving unbrushed portion.

(Experiment 2)

Next, in regard to the brush in which the length of the fiber was set to 7 mm to 12 mm; the diameter thereof was set to 0.10 mm to 0.25 mm; the length of the tapered fiber from the tip part of the tapered surface was set to 1 mm to 8 mm, and the mixing ratio of the tapered fiber was set to 90% or more of the entirety, having shown good feeling of use in Example 1; the number of the fibers forming one bundle of the fibers was set to 40 to 70; the bundle number forming the brush was set to 10 to 25; the planar shape of the brush was set to the rectangular shape; the length of the brush in the longitudinal direction of the handle was set to 10 mm to 25 mm; the length of the brush in the lateral direction of the handle was set to 7 mm to 13 mm; and the bending strength of the toothbrush in a position of 1 mm away from the leading edge of the toothbrush was measured.

As a result, in a case where the number of the fibers forming one bundle of the fibers is set to 42 to 48; the bundle number forming the brush is set to 22; the planar shape of the brush is set to the rectangular shape; the length of the brush in the longitudinal direction of the handle is set to 20 mm and the length of the brush in the lateral direction of the handle is set to 10.8 mm; the bending strength is in a range of 0.60 to 2.00 N/cm²; the bristle tip (tip part of the fiber) has appropriate bending strength and soft feelings and as described before, the brush allows the bristle tip (tip part of the fiber) to enter the narrow location such as the tooth face or periodontal pocket to brush the tooth face, the gum, and the interdentium without leaving unbrushed portion.

(Experiment 3)

Nylon fiber were used as a material of the synthetic resin fiber to produce a toothbrush subjected to mineral coating treatment, and nylon fibers having the tapered surface formed by the above manufacturing method were used to produce a toothbrush subjected to mineral coating treatment. Endurance tests of both the toothbrushes were conducted.

As a result, the toothbrush that used the nylon fiber having the tapered surface formed by the above manufacturing method and was subjected to the mineral coating treatment allows to obtain an effect of the mineral coating treatment for longer hours.

REFERENCE SIGNS LIST

-   1 TOOTHBRUSH -   2 HANDLE OF TOOTHBRUSH -   2 a IMPLANT HOLE -   2 b ENGAGEMENT ELEMENT -   3 BRUSH -   3 a TIP PART -   3 b TAPERED PART -   3 c STRAIGHT BODY PART -   4 SYNTHETIC RESIN FIBER -   4 a TAPERED FIBER -   4 a 1 TAPERED SURFACE -   4 b NON-TAPERED FIBER -   4 b 1 END FACE -   X TAPERED SURFACE LENGTH 

1. A toothbrush comprising: a brush in which a mineral component layer is formed on a surface of a synthetic resin fiber, wherein a tapered surface is formed on the synthetic resin fiber in a range of 1 mm to 8 mm from a tip and the synthetic resin fiber having the tapered surface occupies 90% or more of the synthetic resin fibers forming the brush, and bending strength of the brush at a position of 1 mm from a leading edge of the brush is 0.60 N/cm² to 2.00 N/cm².
 2. The toothbrush according to claim 1, wherein irregularities are formed on the tapered surface.
 3. A manufacturing method of the toothbrush according to claim 1, comprising the steps of: bundling the synthetic resin fibers to produce a synthetic resin fiber assembly; immersing the synthetic resin fiber assembly in a solution bath in which a soluble liquid is accommodated; moving the synthetic resin fiber assembly up and down from an upper side of a polishing/rubbing body; making the synthetic resin fiber assembly come into contact with a polishing/rubbing blade for a predetermined time; dissolving and swelling a surface of the synthetic resin fiber; and scrubbing off the surface of the synthetic resin fiber by the polishing/rubbing blade, to form the tapered surface.
 4. The manufacturing method of the toothbrush according to claim 3, wherein after the step of forming the tapered surface, the synthetic resin fiber assembly is immersed in mineral water to form a mineral component layer. 